EP2164304A2

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Publication number: EP2164304A2
Application number: EP20090175867
Authority: EP
Inventors: Robert C. Newman; Jeremy Nearhoof; Gregory Altonen; Daniel F. Carmen
Original assignee: Lutron Electronics Co Inc
Current assignee: Lutron Technology Co LLC
Priority date: 2006-06-20
Filing date: 2007-06-19
Publication date: 2010-03-17
Anticipated expiration: 2027-06-19
Also published as: US20110018610A1; CN101536611B; BRPI0713362A2; WO2007149417A2; MX2008016236A; US20070289860A1; EP2164303B1; US20110018611A1; EP2164304A3; US7855543B2; WO2007149417A3; EP2164304B1; US8040080B2; US8098029B2; EP2033497B1; CA2655421C; CN101536611A; EP2164303A3; CA2655421A1; EP2033497A2

Abstract

A touch dimmer has a three-wire touch sensitive screen that produces an output voltage signal representative of a position of a manual pressure touch along a longitudinal axis of the touch screen, a filter circuit is coupled to the output of the touch screen to prevent the detection of transient touches, and to prevent the detection of low -pressure touches having less than a certain actuation force. As a result, a controller may accurately determine the position of the manual pressure touch. In a preferred embodiment, two filters are coupled to the output of the touch screen. The first filter conditions the output voltage signal to allow the controller to accurately determine whether a manual pressures touch actuation has occurred. The second filter conditions the output voltage signal to allow the controller to accurately determine the position of the manual pressure touch along a longitudinal axis of the touch screen. An alternative embodiment of the touch dimmer uses a four-wire touch sensitive screen that produces a second output voltage signal representative of a position of a manual pressure touch along a transverse axis of the touch screen. The first filter is coupled to receive the second output signal to permit accurate detection of a manual pressure touch actuation.

Description

BACKGROUND OF THE INVENTIONField of the Invention

The present invention relates to load control devices for controlling the amount of power delivered to an electrical load from a power source. More specifically, the present invention relates to a touch dimmer having a touch sensitive device.

Description of the Related Art

A conventional two-wire dimmer has two terminals: a "hot" terminal for connection to an alternating-current (AC) power supply and a "dimmed hot" terminal for connection to a lighting load. Standard dimmers use one or more semiconductor switches, such as triacs or field effect transistors (FETs), to control the current delivered to the lighting load and thus to control the intensity of the light. The semiconductor switches are typically coupled between the hot and dimmed hot terminals of the dimmer.

Smart wall-mounted dimmers include a user interface typically having a plurality of buttons for receiving inputs from a user and a plurality of status indicators for providing feedback to the user. These smart dimmers typically include a microcontroller or other processing device for providing an advanced set of control features and feedback options to the end user. An example of a smart dimmer is described in greater detail in commonly assigned U.S. Pat. No. 5,248,919, issued on September 28, 1993, entitled LIGHTING CONTROL DEVICE, which is herein incorporated by reference in its entirety,
Fig. 1 is a front view of a user interface of a prior artsmart dimmer switch 10 for controlling the amount of power delivered from a source of AC power to a lighting load. As shown, thedimmer switch 10 includes afaceplate 12, abezel 14, anintensity selection actuator 16 for selecting a desired level of light intensity of a lighting load (not shown) controlled by thedimmer switch 10, and acontrol switch actuator 18. Actuation of theupper portion 16A of theintensity selection actuator 16 increases or raises the light intensity of the lighting load, while actuation of thelower portion 16B of theintensity selection actuator 16 decreases or lowers the light intensity. Theintensity selection actuator 16 may control a rocker switch, two separate push switches, or the like. Thecontrol switch actuator 18 may control a push switch or any other suitable type of actuator and typically provides tactile and auditory feedback to a user when pressed.
Thesmart dimmer 10 also includes an intensity level indicator in the form of a plurality oflight sources 20, such as light-emitting diodes (LEDs).Light sources 20 may be arranged in an array (such as a linear array as shown) representative of a range of light intensity levels of the lighting load being controlled. The intensity level of the lighting load may range from a minimum intensity level, which is preferably the lowest visible intensity, but which may be zero, or "full off," to a maximum intensity level, which is typically "full on." Light intensity level is typically expressed as a percentage of full intensity. Thus, when the lighting load is on, light intensity level may range from 1% to 100%.
By illuminating a selected one of thelight sources 20 depending upon light intensity level, the position of the illuminated light source within the array provides a visual indication of the light intensity relative to the range when the lamp or lamps being controlled are on. For example, seven LEDs are illustrated inFIG. 1. Illuminating the uppermost LED in the array will give an indication that the light intensity level is at or near maximum. Illuminating the center LED will give an indication that the light intensity level is at about the midpoint of the range. In addition, when the lamp or lamps being controlled are off, all of thelight sources 18 are illuminated at a low level of illumination, while the LED representative of the present intensity level in the on state is illuminated at a higher illumination level. This enables the light source array to be more readily perceived by the eye in a darkened environment, which assists a user in locating the switch in a dark room, for example, in order to actuate the switch to control the lights in the room, and provides sufficient contrast between the level-indicating LED and the remaining LEDs to enable a user to perceive the relative intensity level at a glance.
Touch dimmers (or "zip" dimmers) are known in the art. A touch dimmer generally includes a touch-operated input device, such as a resistive or a capacitive touch pad. The touch-operated device responds to the force and position of a point actuation on the surface of the device and in turn controls the semiconductor switches of the dimmer. An example of a touch dimmer is described in greater detail in commonly-assignedU.S. Patent No. 5,196,782, issued March 23, 1993, entitled TOUCH-OPERATED POWER CONTROL, the entire disclosure of which is hereby incorporated by reference.
Fig. 2 is a cross-sectional view of a prior art touch-operateddevice 30, specifically, a membrane voltage divider. Aconductive element 32 and aresistive element 34 are co-extensively supported in close proximity by aspacing frame 36. An input voltage, V_IN, is applied across theresistive element 34 to provide a voltage gradient across its surface. When pressure is applied at apoint 38 along the conductive element 32 (by a finger or the like), the conductive element flexes downward and electrically contacts a corresponding point along the surface of theresistive element 34, providing an output voltage, V_OUT, whose value is between the input voltage V_IN and ground. When pressure is released, theconductive element 32 recovers its original shape and becomes electrically isolated from theresistive element 34. The touch-operateddevice 30 is characterized by a contact resistance R_CONTACT between theconductive element 32 and theresistive element 34. The contact resistance R_CONTACT is dependent upon the force of the actuation of the touch-operateddevice 30 and is typically substantially small for a normal actuation force.
Fig. 3 is a perspective view of a user interface of a priorart touch dimmer 40. Thedimmer 40 comprises a touch-operateddevice 30, which is located directly behind afaceplate 42. Thefaceplate 42 includes aflexible area 44 located directly above theconductive element 32 of the touch-operateddevice 30 to permit a user to actuate the touch-operated device through thefaceplate 42. A conventional phase-control dimming circuit is located within an enclosure 46 and controls the power from a source to a load in accordance with pressure applied to a selectable point onflexible area 44. Thefaceplate 42 may includeoptional markings 48, 50, 52 to indicate, respectively, the location offlexible area 44, the lowest achievable intensity level of the load, and location of a "power off" control. Anoptional LED array 54 provides a visual indication of intensity level of the load. When the load is a light source, there is preferably a linear relationship between the number of illuminated LEDs and the corresponding perceived light level. Theflexible area 44 may optionally include a light transmissive area through whichLED array 54 is visible.
It is desirable to provide a touch dimmer that is responsive to only the position of an actuation on the operational area, e.g., theflexible area 44 of thetouch dimmer 40. However, most prior art touch dimmers are responsive to both the force and the position of a point actuation. For example, when a user lightly presses the touch-operateddevice 30, i.e., with a low actuation force, the contact resistance R_CONTACT is substantially larger than during a normal actuation. Accordingly, the output of the touch-operateddevice 30 is not representative of the position of the actuation and thedimmer 40 may control the lighting load to an undesired intensity level. Therefore, there is a need for a touch dimmer having an operational area that is not responsive to light touches and is responsive to only the position of a point actuation.

SUMMARY OF THE INVENTION

According to the present invention, a load control device for controlling the amount of power delivered to an electrical load from an AC power source, comprises a semiconductor switch, a controller, a touch sensitive actuator, and a stabilizing circuit. The semiconductor switch is operable to be coupled in series electrical connection between the source and the load, the semiconductor switch having a control input for controlling the semiconductor switch between a non-conductive state and a conductive state. The controller is operatively coupled to the control input of the semiconductor switch for controlling the semiconductor switch between the non-conductive state and the conductive state. The touch sensitive actuator has a touch sensitive front surface responsive to a point actuation characterized by a position and a force. The touch sensitive actuator has an output operatively coupled to the controller for providing a control signal to the controller. The stabilizing circuit is coupled to the output of the touch sensitive actuator. The control signal is responsive only to the position of the point actuation.
According to a second embodiment of the present invention, a load control device for controlling the amount of power delivered to an electrical load from an AC power source, the load control device comprises a semiconductor switch, a controller, a touch sensitive actuator, a usage detection circuit, and a stabilizing circuit. The semiconductor switch is operable to be coupled in series electrical connection between the source and the load. The semiconductor switch has a control input for controlling the semiconductor switch between a non-conductive state and a conductive state. The controller is operatively coupled to the control input of the semiconductor switch for controlling the semiconductor switch between the non-conductive state and the conductive state. The touch sensitive actuator having a touch sensitive front surface responsive to a point actuation characterized by a position and a force, the touch sensitive actuator having an output for providing a control signal. The usage detection circuit is operatively coupled between the output of the touch sensitive actuator and the controller for determining whether the point actuation is presently occurring. The stabilizing circuit is operatively coupled between the output of the touch sensitive actuator and the controller for stabilizing the control signal from the output of the touch sensitive actuator. The controller is responsive to the control signal when the usage detection circuit has determined that the point actuation is presently occurring.
According to another aspect of the present invention, in a control circuit for operating an electrical load in response to an output signal from a touch pad, said touch pad comprising an elongated manually touchable resistive area which produces an output signal at an output terminal, said signal representative of the location at which the touch pad is manually touched, said control circuit including a microprocessor having an input connected to said output signal and producing an output for controlling said load in response to the manual input to said touch pad, the improvement comprising a filter capacitor connected between said output terminal and a ground terminal to define a resistive-capacitive circuit with the resistance of said touch pad, said resistive-capacitive circuit characterized by a time constant and being adapted to prevent large transient voltage changes due to low pressure touches of said touch pad.
Further, in a manually operable control structure for producing an electrical signal dependent on the location at which a touch screen is touched; said control structure comprising a resistive touch screen having a control voltage connected to terminals at its opposite ends and an output terminal which is connected to said touch screen at the location of a local manual pressure applied to said screen by a user; a microprocessor having an input connected to said output terminal and producing an output related to the position at which said screen receives said local manual pressure; the improvement which comprises a filter capacitor connected between said output terminal and a ground terminal and defining an R/C circuit with the resistance of said touch screen between said position at which said screen receives local manual pressure and one of its said terminals.
In addition, the present invention provides a process for generating an operating signal from a resistive touch screen in which an output voltage on a output terminal is related to both the location on the screen area which is touched by a users finger and to the pressure of the touch; said process comprising the production of an x signal in response to the touching of said screen at any location on its surface and the production of a y signal in response to the location at which the screen is touched, and applying said x and y signals to a microprocessor; said microprocessor producing an output signal to a circuit to be controlled only when an x output signal is present and a y output signal is also present at the end of a predetermined sample interval.
Other features and advantages of the present invention will become apparent from the following description of the invention that refers to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a front view of a user interface of a prior art dimmer;
Fig. 2 is a cross-sectional view of a prior art touch-operated device;
Fig. 3 is a perspective view of a user interface of a prior art touch dimmer;
Fig. 4A is a perspective view of a touch dimmer according to the present invention;
Fig. 4B is a front view of the touch dimmer ofFig. 4A;
Fig. 5A is a partial assembled sectional view of a bezel and the touch sensitive device of the touch dimmer ofFig. 4A;
Fig. 5B is a partial exploded sectional view of the bezel and the touch sensitive device ofFig. 5A;
Fig. 6 shows the force profiles of the components and a cumulative force profile of the touch dimmer ofFig. 4A;
Fig. 7 is a simplified block diagram of the touch dimmer ofFig. 4A;
Fig. 8 is a simplified schematic diagram of a stabilizing circuit and a usage detection circuit of the touch dimmer ofFig. 7 according to a first embodiment of the present invention;
Fig. 9 is a simplified schematic diagram of an audible sound generator of the touch dimmer ofFig. 7;
Fig. 10 is a flowchart of a touch dimmer procedure executed by a controller of the dimmer ofFig. 4A;
Fig. 11 is a flowchart of an Idle procedure of the touch dimmer procedure ofFig. 10;
Figs. 12A and12B are flowcharts of an ActiveHold procedure of the touch dimmer procedure ofFig. 10;
Fig. 13 is a flowchart of a Release procedure of the touch dimmer procedure ofFig. 10;
Figs. 14A and14B are simplified schematic diagrams of the circuitry for a four wire touch sensitive device and a controller of the touch dimmer ofFig. 4A according to a second embodiment of the present invention;
Fig. 15A is a simplified schematic diagram of the circuitry for a four wire touch sensitive device and a controller of the touch dimmer ofFig. 4A according to a third embodiment of the present invention;
Fig. 15B is a simplified block diagram of a dimmer according to a fourth embodiment of the present invention;
Fig. 15C is a simplified schematic diagram of the circuitry for a three-wire touch sensitive device and a controller of the dimmer ofFig. 15B.
Fig. 16A is a perspective view of a touch dimmer according to a fifth embodiment of the present invention;
Fig. 16B is a front view of the touch dimmer ofFig. 16A;
Fig. 17A is a bottom cross-sectional view of the touch dimmer ofFig. 16B;
Fig. 17B is an enlarged partial view of the bottom cross-sectional view ofFig. 17A;
Fig. 18A is a left side cross-sectional view of the touch dimmer ofFig. 16B;
Fig. 18B is an enlarged partial view of the left side cross-sectional viewFig. 18A;
Fig. 19 is a perspective view of a display printed circuit board of the dimmer ofFig. 16A; and
Fig. 20 is an enlarged partial bottom cross-sectional view of a thin touch sensitive actuator according to a sixth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purposes of illustrating the invention there is shown in the drawings an embodiment that is presently preferred, in which like numerals represent similar parts throughout the several views of the drawings, it being understood, however, that the invention is not limited to the specific methods and instrumentalities disclosed.
Figs. 4A and4B are a perspective view and a front view, respectively, of a touch dimmer 100 according to the present invention. The dimmer 100 includes afaceplate 102, i.e., a cover plate, having a planarfront surface 103 and anopening 104. Theopening 104 may define a standard industry-defined opening, such as a traditional opening or a decorator opening, or another uniquely-sized opening as shown inFig. 4A. Abezel 106 having a planar touch sensitivefront surface 108 extends through theopening 104 of thefaceplate 102. Thefront surface 108 of thebezel 106 is positioned immediately above a touch sensitive device 110 (shown inFigs. 5A and 5B), i.e., a touch sensitive element, such that a user of the dimmer 100 actuates the touchsensitive element 110 by pressing thefront surface 108 of thebezel 106. As shown inFig. 4A, thefront surface 108 of thebezel 106 is substantially flush with thefront surface 103 of thefaceplate 102, i.e., the plane of thefront surface 108 of thebezel 106 is coplanar with the plane of thefront surface 103 of thefaceplate 102. However, thebezel 106 may extend through theopening 104 of thefaceplate 102 such that thefront surface 108 of the bezel is provided in a plane above the plane of thefront surface 103 of thefaceplate 102. Thefaceplate 102 is connected to anadapter 109, which is connected to a yoke (not shown). The yoke is adapted to mount the dimmer 100 to a standard electrical wallbox.
The dimmer 100 further comprises a visual display, e.g., a plurality ofstatus markers 112 provided in a linear array along an edge of thefront surface 108 of thebezel 106. Thestatus markers 112 are preferably illuminated from behind bystatus indicators 114, e.g., light-emitting diodes (LEDs), located internal to the dimmer 100 (seeFig. 7). The dimmer 100 preferably comprises a light pipe (not shown) having a plurality of light conductors to conduct the light from thestatus indicators 114 inside the dimmer to themarkers 12 on thefront surface 108 of thebezel 106. Thestatus indicators 114 behind themarkers 112 are preferably blue. As shown inFigs. 4A and4B, the dimmer 100 comprises seven (7)status markers 112. However, the dimmer 100 may comprise any number of status markers. Further, thestatus markers 112 may be disposed in a vertical linear array along the center of thefront surface 108 of thebezel 106. Themarkers 112 may comprise shadows apparent on thefront surface 108 due to voids behind the front surface.
Thefront surface 108 of thebezel 106 further includes anicon 116. Theicon 116 may be any sort of visual marker, such as, for example, a dot. Upon actuation of the lower portion of thefront surface 108 surrounding theicon 116, the dimmer 100 causes a connected lighting load 208 (Fig. 7) to change from on to off (and vice versa), i.e., to toggle. Preferably, a blue status indicator and an orange status indicator are located immediately behind theicon 116, such that theicon 116 is illuminated with blue light when thelighting load 208 is on and illuminated with orange light when the lighting load is off. Actuation of the upper portion of thefront surface 108, i.e., above the portion surrounding theicon 116, causes the intensity of thelighting load 208 to change. Thestatus indicators 114 behind thestatus markers 112 are illuminated to display the intensity of thelighting load 208. For example, if thelighting load 208 is at 50% lighting intensity, the middle status indicator will be illuminated. Preferably, the dimmer 100 does not respond to actuations in akeepout region 118 of thefront surface 108. Thekeepout region 118 prevents inadvertent actuation of an undesired portion of thefront surface 10 during operation of the dimmer 100.
The dimmer 100 further includes anairgap switch actuator 119. Pulling theairgap switch actuator 119 opens a mechanical airgap switch 219 (Fig. 7) inside the dimmer 100 and disconnects thelighting load 208 from a connected AC voltage source 204 (Fig. 7). Theairgap switch actuator 119 extends only sufficiently above thefront surface 103 of thefaceplate 102 to be gripped by a fingernail of a user. The electronic circuitry of the dimmer 100 (to be described in greater detail below) is mounted on a printed circuit board (PCB) (not shown). The PCB is housed in an enclosure (not shown), i.e., an enclosed volume, which is attached to the yoke of the dimmer 100.
Fig. 5A is a partial assembled sectional view andFig. 5B is a partial exploded sectional view of thebezel 108 and the touchsensitive device 110 of the dimmer 100 according to the present invention. The touchsensitive device 110 comprises, for example, a resistive divider, and operates in a similar fashion as the touch-operateddevice 30 of the priorart touch dimmer 40. The touchsensitive device 110 includes aconductive element 120 and aresistive element 122 supported by aspacing frame 124. However, the touchsensitive device 110 may comprise a capacitive touch screen or any other type of touch responsive clement. Such touch sensitive devices are often referred to as touch pads or touch screens.
Anelastomer 126 is received by anopening 128 in the rear surface of thebezel 106. Theelastomer 126 is positioned between thebezel 106 and the touchsensitive device 110, such that a press on thefront surface 108 of the bezel is transmitted to theconductive element 120 of the touchsensitive device 110. Preferably, theelastomer 126 is made of rubber and is 0.040" thick. Theelastomer 126 preferably has a durometer of 40A, but may have a durometer in the range of 20A to 80A. Theconductive element 120 and theresistive element 122 of the touchsensitive device 110 and theelastomer 126 are preferably manufactured from a transparent material such that the light from the plurality ofstatus indicators 114 inside the dimmer 100 are operable to shine through the touchsensitive device 110 and theelastomer 126 tofront surface 108 of thebezel 106.
The position and size of the touchsensitive device 110 is demonstrated by the dotted line inFig. 4B. The touchsensitive device 110 has a length L₁ and a width W₁ that is larger than a length L₂ and a width W₂ of thefront surface 108 of thebezel 106. Accordingly, a first area A₁ of the surface of touch sensitive device 110 (i.e., A₁ = L₁ · W₁) is greater than a second area A₂ of thefront surface 108 of the bezel 106 (i.e., A₂ = L₂ · W₂). An orthogonal projection of the second area Az onto the first area A₁ is encompassed by the first area A₁, such that a point actuation at any point on thefront surface 108 of thebezel 106 is transmitted to theconductive element 120 of the touchsensitive device 110. As shown inFigs. 4A and4B, the length L₂ of thefront surface 108 of thebezel 106 is approximately four (4) times greater than the width W₂. Preferably, the length L₂ of thefront surface 108 of thebezel 106 is four (4) to six (6) times greater than the width W₂. Alternatively, thefront surface 108 of thebezel 106 may be provided in an opening of a decorator-style faceplate
Fig. 6 shows the force profiles of the components of the dimmer 100 shown inFigs. 5A and 5B and a cumulative force profile for the touchsensitive device 110 of the dimmer 100. Each of the force profiles shows the force required to actuate the touchsensitive device 110 with respect to the position of the point actuation. The force profile represents the amount of force required to displace the element by a given amount. While the force profiles inFig. 6 are shown with respect to the widths of the components of the dimmer 100, a similar force profile is also provided along the length of the components.
Fig. 6(a) shows a force profile of thebezel 106. Thebezel 106 has substantiallythin sidewalls 129, e.g., 0.010" thick, such that thebezel 106 exhibits a substantially flat force profile.Fig. 6(b) shows a force profile of the touchsensitive device 110. The force required to actuate the touchsensitive device 110 increases near the edges because of the spacing frames 124.Fig. 6(c) shows a force profile of theelastomer 126. The force profile of the elastomer 125 is substantially flat, i.e., a force at any point on the front surface of theelastomer 126 will result in a substantially equal force at the corresponding point on the rear surface.
Fig. 6(d) is a total force profile of thetouch dimmer 100. The individual force profiles shown inFigs. 6(a) - 6(c) are additive to create the total force profile. The total force profile is substantially flat across the second area A₂ of thefront surface 108 of thebezel 106. This means that a substantially equal minimum actuation force f_MIN is required to actuate the touchsensitive device 110 at all points of thefront surface 108 of thebezel 106, even around the edges. Accordingly, the dimmer 100 of the present invention provides a maximum operational area in an opening of a faceplate, i.e., substantially all of the second area A₂ of thefront surface 108 of thebezel 106, which is an improvement over the prior art touch dimmers. The minimum actuation force f_MIN is substantially equal at all points on thefront surface 108 of thebezel 106. For example, the minimum actuation force f_MIN may be 20 grams.
Fig. 7 is a simplified block diagram of the touch dimmer 100 according to the present invention. The dimmer 100 has ahot terminal 202 connected to anAC voltage source 204 and a dimmedhot terminal 206 connected to alighting load 208. The dimmer 100 employs abidirectional semiconductor switch 210 coupled between thehot terminal 202 and the dimmedhot terminal 206, to control the current through, and thus the intensity of, thelighting load 208. Thesemiconductor switch 210 has a control input (or gate), which is connected to agate drive circuit 212. The input to the gate renders thesemiconductor switch 210 selectively conductive or non-conductive, which in turn controls the power supplied to thelighting load 208, Thegate drive circuit 212 provides a control input to thesemiconductor switch 210 in response to a control signal from acontroller 214. Thecontroller 214 may be any suitable controller, such as a microcontroller, a microprocessor, a programmable logic device (PLD), or an application specific integrated circuit (ASIC).
A zero-crossing detectcircuit 216 determines the zero-crossing points of the AC source voltage from theAC power supply 204. A zero-crossing is defined as the time at which the AC supply voltage transitions from positive to negative polarity, or from negative to positive polarity, at the beginning of each half-cycle. The zero-crossing information is provided as an input to thecontroller 214. Thecontroller 214 generates the gate control signals to operate thesemiconductor switch 210 to thus provide voltage from theAC power supply 204 to thelighting load 208 at predetermined times relative to the zero-crossing points of the AC waveform. Apower supply 218 generates a direct-current (DC) voltage V_CC, e.g., 5 volts, to power thecontroller 214 and other low voltage circuitry of the dimmer 100.
The touchsensitive device 110 is coupled to thecontroller 214 through a stabilizingcircuit 220 and ausage detection circuit 222. The stabilizingcircuit 220 is operable to stabilize the voltage output of the touchsensitive device 110. Accordingly, the voltage output of the stabilizingcircuit 220 is not dependent on the magnitude of the force of the point actuation on the touchsensitive device 110, but rather is dependent solely on the position of the point actuation. Theusage detection circuit 222 is operable to detect when a user is actuating thefront surface 108 of the dimmer 100. Thecontroller 214 is operable to couple and decouple the stabilizingcircuit 220 and theusage detection circuit 222 from the output of the touchsensitive device 110. The controller is further operable to receive control signals from both the stabilizingcircuit 220 and theusage detection circuit 222. Preferably, the stabilizingcircuit 220 has a slow response time, while theusage detection circuit 222 has a fast response time. Thus, thecontroller 214 is operable to control thesemiconductor switch 210 in response to the control signal provided by the stabilizingcircuit 220 when theusage detection circuit 222 has detected an actuation of the touchsensitive device 110.
Thecontroller 214 is operable to drive the plurality ofstatus indicators 114, e.g., light-emitting diodes (LEDs), which are located behind themarkers 112 on thefront surface 108 of the dimmer 100. Thestatus indicators 114 also comprise the blue status indicator and the orange status indicator that are located immediately behind theicon 116. The blue status indicator and the orange status indicator may be implemented as separate blue and orange LEDs, respectively, or as a single bi-colored LED.
The dimmer 100 further comprises anaudible sound generator 224 coupled to thecontroller 214, such that the controller is operable to cause the sound generator to produce an audible sound in response to an actuation of the touchsensitive device 110. Amemory 225 is coupled to thecontroller 214 and is operable to store control information of the dimmer 100.
Fig. 8 is a simplified schematic diagram of the circuitry for the touchsensitive device 110 and thecontroller 214, i.e., the stabilizingcircuit 220 and theusage detection circuit 222, according to a first embodiment of the present invention. Theresistive element 122 of the touchsensitive device 110 is coupled between the DC voltage V_CC of thepower supply 218 and circuit common, such that the DC voltage V_CC provides a biasing voltage to the touch sensitive device. For example, theresistive element 122 may have a resistance R_E of 7.6 kΩ. The position of contact between theconductive element 120 and theresistive element 122 of the touchsensitive device 110 is determined by the position of a point actuation on thefront surface 108 of thebezel 106 of the dimmer 100. Theconductive element 120 is coupled to both the stabilizingcircuit 220 and theusage detection circuit 222. As shown inFig. 7, the touchsensitive device 110 of the dimmer 100 of the first embodiment is a three-wire device, i.e., the touch sensitive device has three connections or electrodes. The touch sensitive device provides one output that is representative of the position of the point actuation along a Y-axis, i.e., a longitudinal axis of the dimmer 100 as shown inFig. 4B.
The stabilizingcircuit 220 comprises a whacking-grade capacitor C230 (that is, a capacitor having a large value of capacitance) and afirst switch 232. Thecontroller 214 is operable to control thefirst switch 232 between a conductive state and a non-conductive state. When thefirst switch 232 is conductive, the capacitor C230 is coupled to the output of the touchsensitive device 110, such that the output voltage is filtered by the capacitor C230, When a touch is present, the voltage on the capacitor C230 will be forced to a steady-state voltage representing the position of the touch on thefront surface 108. When no touch is present, the voltage on the capacitor will remain at a voltage representing the position of the last touch. The touchsensitive device 110 and the capacitor C230 form a sample-and-hold circuit. The response time of the sample-and-hold circuit is determined by a resistance R_D of the touch sensitive device (i.e., the resistance R_E of the resistive element and a contact resistance R_C) and the capacitance of the capacitor C230. During typical actuation, the contact resistance R_C is small compared to the value of R_E. such that a first charging time constant τ₁ is approximately equal to R_E · C₂₃₀. This time constant τ₁is preferably 13 ms, but may be anywhere between 6ms and 15ms.
When a light or transient press is applied to the touchsensitive device 110, the capacitor C230 will continue to hold the output at the voltage representing the position of the last touch. During the release of the touchsensitive device 110, transient events may occur that produce output voltages that represent positions other than the actual touch position. Transient presses that are shorter than the first charging time constant τ₁ will not substantially affect the voltage on the capacitor C230, and therefore will not substantially affect the sensing of the position of the last actuation. During a light press, a second charging time constant τ₂ will be substantially longer than during normal presses, i.e., substantially larger than the first time constant τ₁, due to the higher contact resistance R_C. However, the steady-state value of the voltage across the capacitor C230 will be the same as for a normal press at the same position. Therefore, the output of the stabilizingcircuit 220 is representative of only the position of the point of actuation of the touchsensitive device 110.
Theusage detection circuit 222 comprises a resistor R234, a capacitor C236, and asecond switch 238, which is controlled by thecontroller 214. When theswitch 238 is conductive, the parallel combination of the resistor R234 and the capacitor C236 is couple to the output of the touchsensitive device 110. Preferably, the capacitor C236 has a substantially small capacitance C₂₃₆, such that the capacitor C236 charges substantially quickly in response to all point actuations on thefront surface 108. The resistor R234 allows the capacitor C236 to discharge quickly when theswitch 238 is non-conductive. Therefore, the output of theusage detection circuit 222 is representative of the instantaneous usage of the touchsensitive device 110.
Thecontroller 214 controls theswitches 232, 238 in a complementary manner. When thefirst switch 232 is conductive, thesecond switch 238 is non-conductive, and vice versa. Thecontroller 214 controls thesecond switch 238 to be conductive for a short period of time t_USAGE once every half cycle of thevoltage source 204 to determine whether the user is actuating thefront surface 108. Preferably, the short period of time t_USAGE is approximately 100 µsec or 1% of the half-cycle (assuming each half-cycle is 8.33 msec long). For the remainder of the time, thefirst switch 232 is conductive, such that the capacitor C234 is operable to charge accordingly. When thefirst switch 232 is non-conductive and thesecond switch 238 is conductive, the whacking-grade capacitor C230 of the stabilizingcircuit 220 is unable to discharge at a significant rate, and thus the voltage developed across the capacitor C230 will not change significantly when thecontroller 214 is determining whether the touchsensitive device 110 is being actuated through theusage detection circuit 222. While the stabilizingcircuit 220 is shown and described as a hardware circuit in the present application, thecontroller 214 could alternatively provide the filtering functionality of the stabilizing circuit entirely in software.
Fig. 9 is a simplified schematic diagram of theaudible sound generator 224 of the dimmer 100. Theaudible sound generator 224 uses an audio power amplifier integrated circuit (IC) 240, for example, part number TPA721 manufactured by Texas Instruments, Inc., to generate a sound from a piezoelectric ormagnetic speaker 242. Theamplifier IC 240 is coupled to the DC voltage V_CC (pin 6) and circuit common (pin 7) to power the amplifier IC. A capacitor C244 (preferably having a capacitance of 0.1 µF) is coupled between the DC voltage V_CC and circuit common to decouple the power supply voltage and to ensure the output total harmonic distortion (THD) is as low as possible.
Theaudible sound generator 224 receives a SOUND ENABLE signal 246 from thecontroller 214. The SOUND ENABLE signal 246 is provided to an enable pin (i.e., pin 1) on theamplifier IC 240, such that theaudible sound generator 224 will be operable to generate the sound when the SOUND ENABLE signal is at a logic high level.
The audible sound generate 224 further receives a SOUND WAVE signal 248 from thecontroller 214. TheSOUND WAVE signal 248 is an audio signal that is amplified by theamplifier IC 240 to generate the appropriate sound at thespeaker 242. TheSOUND WAVE signal 248 is first filtered by a low-pass filter comprising a resistor R250 and a capacitor C252. Preferably, the resistor R250 has a resistance of 1 kΩ and the capacitor C252 has a capacitance of 0.1 nF. The filtered signal is then passed through a capacitor C254 to produce an input signal V_IN. The capacitor C254 allows the amplifier IC to bias the input signal V_IN to the proper DC level for optimum operation and preferably has a capacitance of 0.1 µF. The input signal V_IN is provided to a negative input (pin 4) of theamplifier IC 240 through a input resistor R_I. A positive input (pin 3) of theamplifier IC 240 and with a bypass pin (pin 2) are coupled to circuit common through a bypass capacitor C256 (preferably, having a capacitance of 0.1 µF).
The output signal V_OUT of theamplifier IC 240 is produced from a positive output (pin 5) to a negative output (pin 8) and is provided to thespeaker 242. The negative input (pin 4) is coupled to the positive output (pin 5) through an output resistor R_F. The gain of theamplifier IC 240 is set by the input resistor R_I and the feedback resistor R_F, i.e., $Gain = V_{OUT} / V_{IN} = - 2 \cdot (R_{F} / R_{I}) .$
Preferably, the input resistor R_I and the output resistor R_F both have resistances of 10 kΩ, such that the gain of theamplifier IC 240 is negative two (-2).
Fig. 10 is a flowchart of atouch dimmer procedure 300 executed by thecontroller 214 of the dimmer 100 according to the present invention. Preferably, thetouch dimmer procedure 300 is called from the main loop of the software of thecontroller 214 once every half cycle of theAC voltage source 204. Thetouch dimmer procedure 300 selectively executes one of three procedures depending upon the state of the dimmer 100. If the dimmer 100 is in an "Idle" state (i.e., the user is not actuating the touch sensitive device 110) atstep 310, thecontroller 214 executes anIdle procedure 400. If the dimmer 100 is in an "ActiveHold" state (i.e., the user is presently actuating the touch sensitive device 110) atstep 320, thecontroller 214 executes anActiveHold procedure 500. If the dimmer 100 is in a "Release" state (i.e., the user has recently ceased actuating the touch sensitive device 110) atstep 330, thecontroller 214 executes aRelease procedure 600.
Fig. 11 is a flowchart of theIdle procedure 400 according to the present invention. Thecontroller 114 uses a "sound flag" and a "sound counter" to determine when to cause theaudible sound generator 224 to generate the audible sound. The purpose of the sound flag is to cause the sound to be generated the first time that thecontroller 214 executes theActiveHold procedure 500 after being in the Idle state. If the sound flag is set, thecontroller 214 will cause the sound to be generated. The sound counter is used to ensure that thecontroller 214 does not cause theaudible sound generator 224 to generate the audible sound too often. The sound counter preferably has a maximum sound counter value S_MAX, e.g., approximately 425 msec. Accordingly, there is a gap of approximately 425 msec between generations of the audible sound. The sound counter is started during theRelease procedure 600 as will be described in greater detail below. Referring toFig. 11, upon entering the Idle state, thecontroller 214 sets the sound flag atstep 404 if the sound flag is not set atstep 402.
An "LED counter" and an "LED mode" are used by thecontroller 214 to control the status indicators 114 (i.e., the LEDs) of the dimmer 100. Thecontroller 214 uses the LED counter to determine when a predetermined time t_LED has expired since the touchsensitive device 110 was actuated. When the predetermined time t_LED has expired, thecontroller 214 will change the LED mode from "active" to "inactive". When the LED mode is "active", thestatus indicators 114 are controlled such that one or more of the status indicators are illuminated to a bright level. When the predetermined time t_LED expires, the LED mode is changed to "inactive", i.e., thestatus indicators 114 are controlled such that one or more of the status indicators are illuminated to a dim level. Referring toFig. 11, if the LED counter is less than a maximum LED counter value L_MAX atstep 410, the LED counter is incremented atstep 412 and the process moves on to step 418. However, if the LED counter is not less than the maximum LED counter value L_MAX, the LED counter is cleared atstep 414 and the LED mode is set to inactive atstep 416. Since thetouch dimmer procedure 300 is executed once every half cycle, the predetermined time t_LED is preferably equal to $t_{LED} = T_{HALF} \cdot L_{MAX,}$
where T_HALF is the period of a half cycle.
Next, thecontroller 214 reads the output of theusage detection circuit 222 to determine if the touchsensitive device 110 is being actuated. Preferably, theusage detection circuit 222 is monitored once every half cycle of thevoltage source 204. Atstep 418, thecontroller 214 opensswitch 232 and closes switch 238 to couple the resistor R234 and the capacitor C236 to the output of the touchsensitive device 110. Thecontroller 214 determines the DC voltage of the output of theusage detection circuit 222 atstep 420, preferably, by using an analog-to-digital converter (ADC). Next, thecontroller 214 closes switch 232 and opensswitch 238 atstep 422.
Atstep 424, if there is activity on thefront surface 108 of the dimmer 100, i.e., if the DC voltage determined atstep 420 is above a predetermined minimum voltage threshold, then an "activity counter" is incremented atstep 426. Otherwise, the activity counter is cleared atstep 428. The activity counter is used by thecontroller 214 to determine if the DC voltage determined atstep 420 is the result of a point actuation of the touchsensitive device 110 rather than noise or some other undesired impulse. The use of the activity counter is similar to a software "debouncing" procedure for a mechanical switch, which is well known in the art. If the activity counter is not less than a maximum activity counter value A_MAX atstep 430, then the dimmer state is set to the ActiveHold state atstep 432. Otherwise, the process simply exits atstep 434.
Figs. 12A and12B are flowcharts of theActiveHold procedure 500, which is executed once every half cycle when the touchsensitive device 110 is being actuated, i.e., when the dimmer 100 is in the ActiveHold state. First, a determination is made as to whether the user has stopped using, i.e., released, the touchsensitive device 110. Thecontroller 214 opensswitch 232 and closes switch 238 atstep 510, and reads the output of theusage detection circuit 222 atstep 512. Atstep 514, thecontroller 214 closes switch 232 and opensswitch 238. If there is no activity on thefront surface 108 of the dimmer 100 atstep 516, thecontroller 214 increments an "inactivity counter" atstep 518. Thecontroller 214 uses the inactivity counter to make sure that the user is not actuating the touchsensitive device 110 before entering the Release mode. If the inactivity counter is less than a maximum inactivity counter value I_MAX atstep 520, the process exits atstep 538. Otherwise, the dimmer state is set to the Release state atstep 522, and then the process exits.
If there is activity on the touchsensitive device 110 atstep 516, thecontroller 214 reads the output of the stabilizingcircuit 220, which is representative of the position of the point actuation on thefront surface 108 of the dimmer 100. Since theswitch 232 is conductive and theswitch 238 is non-conductive, thecontroller 214 determines the DC voltage at the output of the stabilizingcircuit 220, preferably using an ADC, atstep 524.
Next, thecontroller 214 uses a buffer to "filter" the output of stabilizingcircuit 220. When a user actuates the touchsensitive device 110, the capacitor C230 will charge to approximately the steady-state voltage representing the position of the actuation on thefront surface 108 across a period of time determined by the first time constant τ₁ as previously described. Since the voltage across the capacitor C230, i.e., the output of the stabilizingcircuit 220, is increasing during this time, thecontroller 214 delays for a predetermined period of time atstep 525, preferably, for approximately three (3) half cycles.
When a user's finger is removed from thefront surface 108 of thebezel 106, subtle changes in the force and position of the point actuation occur, i.e., a "finger roll-off" event occurs. Accordingly, the output signal of the touchsensitive device 110 is no longer representative of the position of the point actuation. To prevent thecontroller 214 from processing reads during a finger roll-off event, thecontroller 214 saves the reads in the buffer and processes the reads with a delay, e.g., six half cycles later. Specifically, when the delay is over atstep 525, thecontroller 214 rotates the new read (i.e., from step 524) into the buffer atstep 526. If the buffer has at least six reads atstep 528, thecontroller 214 averages the reads in the fifth and sixth positions in the buffer atstep 530 to produce the touch position data. In this way, when the user stops actuating the touchsensitive device 110, thecontroller 214 detects this change atstep 516 and sets the dimmer state to the Release state atstep 522 before the controller processes the reads saved in the buffer near the transition time of the touch sensitive device.
Atstep 532, thecontroller 114 determines if the touch position data fromstep 530 is in the keepout region 118 (as shown inFig. 4B). If the touch position data is in thekeepout region 118, theActiveHold procedure 500 simply exits atstep 538. Otherwise, a determination is made atstep 534 as to whether the sound should be generated. Specifically, if the sound flag is set and if the sound counter has reached a maximum sound counter value S_MAX, thecontroller 214 drives the SOUND ENABLE signal 246 high and provides theSOUND WAVE signal 248 to theaudible sound generator 224 to generate the sound atstep 535. Further, the sound flag is cleared atstep 536 such that the sound will not be generated as long as the dimmer 100 remains in the ActiveHold state.
If the touch position data is in the toggle area, i.e., the lower portion of thefront surface 108 of thebezel 106 surrounding the icon 116 (as shown inFig. 4A), atstep 540, thecontroller 214 processes the actuation of the touchsensitive device 110 as a toggle. If thelighting load 208 is presently off atstep 542, thecontroller 214 turns the lighting load on. Specifically, thecontroller 214 illuminates theicon 116 with the blue status indicator atstep 544 and dims thelighting load 208 up to the preset level, i.e., the desired lighting intensity of the lighting load, atstep 546. If the lighting load is presently on atstep 542, thecontroller 214 turns on the orange status indicator behind theicon 116 atstep 548 and fades thelighting load 208 to off atstep 550.
If the touch position data is not in the toggle area atstep 540, thecontroller 214 scales the touch position data atstep 552. The output of the stabilizingcircuit 220 is a DC voltage between a maximum value, i.e., substantially the DC voltage V_CC, and a minimum value, which corresponds to the DC voltage providing by the touchsensitive device 110 when a user is actuating the lower end of the upper portion of thefront surface 108 of thebezel 106. Thecontroller 214 scales this DC voltage to be a value between off (i.e., 1%) and full intensity (i.e., 100%) of thelighting load 208. Atstep 554, thecontroller 214 dims thelighting load 208 to the scaled level produced instep 552.
Next, thecontroller 214 changes thestatus indicators 114 located behind themarkers 112 on thefront surface 108 of thebezel 106. As a user actuates the touchsensitive device 110 to change intensity of thelighting load 208, thecontroller 214 decides whether to change thestatus indicator 114 that is presently illuminated. Since there are seven (7) status indicators to indicate an intensity between 1% and 100%, thecontroller 214 may illuminate the first status indicator, i.e., the lowest status indicator, to represent an intensity between 1% and 14%, the second status indicator to represent an intensity between 15% and 28%, and so on. The seventh status indicator, i.e., the highest status indicator, may be illuminated to represent an intensity between 85% and 100%. Preferably, thecontroller 214 uses hysteresis to control thestatus indicators 114 such that if the user actuates thefront surface 108 at a boundary between two of the regions of intensities described above, consecutive status indicators do not toggle back and forth.
Referring toFig. 12B, a determination is made as to whether a change is needed as to which status indicator is illuminated atstep 556. If the present LED (in result to the touch position data from step 530) is the same as the previous LED, then no change in the LED is required. The present LED is set the same as the previous LED atstep 558, a hysteresis counter is cleared atstep 560, and the process exits atstep 570.
If the present LED is not the same as the previous LED atstep 556, thecontroller 214 determines if the LED should be changed. Specifically, atstep 562, thecontroller 214 determines if present LED would change if the light level changed by 2% from the light level indicated by the touch position data. If not, the hysteresis counter is cleared atstep 560 and the process exits atstep 570. Otherwise, the hysteresis counter is incremented atstep 564. If the hysteresis counter is less than a maximum hysteresis counter value H_MAX atstep 566, the process exits atstep 570. Otherwise, the LEDs are changed accordingly based on the touch position data atstep 568.
Fig. 13 is a flowchart of theRelease procedure 600, which is executed after thecontroller 214 sets the dimmer state to the Release state atstep 522 of theActiveHold procedure 500. First, a save flag is set atstep 610. Next, the sound counter is reset atstep 612 to ensure that the sound will not be generated again, e.g., for preferably 18 half cycles. Atstep 618, a determination is made as to whether the dimmer 100 is presently executed a fade-to-off If not, the present level is saved as the preset level in thememory 225 atstep 620. Otherwise, the desired lighting intensity is set to off atstep 622, the long fade countdown in started atstep 624, and the preset level is saved as off in thememory 225.
Fig. 14A andFig. 14B are simplified schematic diagrams of the circuitry for a four-wire touchsensitive device 710 and acontroller 714 according to a second embodiment of the present invention. The four-wire touchsensitive device 710 has four connections, i.e., electrodes, and provides two outputs: a first output representative of the position of a point actuation along the Y-axis, i.e., the longitudinal axis of the dimmer 100 a shown inFig. 4B, and a second output representative of the position of the point actuation along the X-axis, i.e., an axis perpendicular to the longitudinal axis. The four-wire touchsensitive device 710 provides the outputs depending on how the DC voltage V_CC is connected to the touch sensitive device. A stabilizingcircuit 720 is operatively coupled to the first output and ausage detection circuit 722 is operatively coupled to the second output.
Thecontroller 714 controls threeswitches 760, 762, 764 to connect the touchsensitive device 710 to the DC voltage V_CC accordingly. When the switches 760,762, 764 are connected in position A as shown inFig. 14A, the DC voltage V_CC is coupled across the Y-axis resistor, and the X-axis resistor provides the output to the stabilizingcircuit 720. When theswitches 760, 762, 764 are connected in position B as shown inFig. 14B, the DC voltage V_CC is coupled across the X-axis resistor, and the Y-axis resistor provides the output to theusage detection circuit 722. Since thecontroller 714 provides one output signal to control whether the stabilizingcircuit 720 or theusage detection circuit 722 is coupled to the touchsensitive device 110, the software executed by thecontroller 714 is the same as the software executed by thecontroller 214 shown inFigs. 10-13.
Fig. 15A is a simplified schematic diagram of the circuitry for the four-wire touchsensitive device 710 and acontroller 814 according to a third embodiment of the present invention. Thecontroller 814 is operable to read the position of a point actuation on the four-wire touchsensitive device 710 along both the Y-axis and the X-axis. When determining the position along the Y-axis, thecontroller 814 operates the same as thecontroller 714 shown inFigs. 14A and14B by controlling theswitches 760, 762, 764 as described above.
An additional stabilizingcircuit 870 is provided for determining the position of the point actuation along the X-axis. The additional stabilizingcircuit 870 comprises a whacking-grade capacitor C872. Thecontroller 814 controls aswitch 874 to selectively switch the output of the X-axis between theusage detection circuit 722 and the additional stabilizingcircuit 870. Thecontroller 814 controls theswitch 874 in a similar fashion to how thecontroller 214 controls theswitches 232, 238 (as shown inFig. 8).
Fig. 15B is a simplified block diagram of a dimmer 1000 according to a fourth embodiment of the present invention.Fig. 15C is a simplified schematic diagram of the circuitry for the three-wire touchsensitive device 110 and acontroller 1014 of the dimmer 1000 according to the fourth embodiment. The dimmer 1000 comprises only a stabilizingcircuit 1020 and does not comprise a usage detection circuit. The stabilizingcircuit 1020 only comprises a whacking-grade capacitor C1030. Accordingly, thecontroller 1014 is not operable to control the stabilizingcircuit 1020 and is responsive to the touchsensitive device 100 through only the stabilizing circuit.
Figs. 16A and16B are a perspective view and a front view, respectively, of a touch dimmer 900 according to a fifth embodiment of the present invention.Fig. 17A is a bottom cross-sectional view andFig. 17B is an enlarged partial bottom cross-sectional view of the dimmer 900.Fig. 18A is a left side cross-sectional view andFig. 18B is an enlarged partial left side cross-sectional view of the dimmer 900.
Thetouch dimmer 900 includes a thin touchsensitive actuator 910 comprising anactuation member 912 extending through abezel 914. The dimmer 900 further comprises afaceplate 916, which has anon-standard opening 918 and mounts to anadapter 920. Thebezel 914 is housed behind thefaceplate 916 and extends through theopening 918. Theadapter 920 connects to ayoke 922, which is adapted to mount the dimmer 900 to a standard electrical wallbox. A main printed circuit board (PCB) 924 is mounted inside anenclosure 926 and includes the some of the electrical circuitry of the dimmer 200, e.g., thesemiconductor switch 210, thegate drive circuit 212, thecontroller 214, the zero-crossing detectcircuit 216, thepower supply 218, the stabilizingcircuit 220, theusage detection circuit 222, theaudible sound generator 224, and thememory 225, of the dimmer 200. The thin touchsensitive actuator 910 preferably extends beyond the faceplate by 1/16", i.e., has a height of 1/16", but may have a height in the range of 1/32" to 3/32". Preferably, the touchsensitive actuator 910 has a length of 3-5/8" and a width of 3/16". However, the length and the width of the touchsensitive actuator 910 may be in the ranges of 2-5/8" - 4" and 1/8" - 1/4", respectively.
The touchsensitive actuator 910 operates to contact a touchsensitive device 930 inside thetouch dimmer 900. The touchsensitive device 930 is contained by abase 932. Theactuation member 912 includes a plurality oflong posts 934, which contact the front surface of the touchsensitive device 930 and are arranged in a linear array along the length of the actuation member. Theposts 934 act as force concentrators to concentrate the force from an actuation of theactuation member 912 to the touchsensitive device 930.
A plurality ofstatus indicators 936 are arranged in a linear array behind theactuation member 912. The status indicators are mounted on adisplay PCB 938, i.e., a status indicator support board, which is mounted between the touchsensitive device 930 and thebezel 914.Fig. 19 is a perspective view of thedisplay PCB 938. Thedisplay PCB 938 includes a plurality ofholes 939, which thelong posts 934 extend through to contact the touchsensitive device 930. Theactuation member 912 is preferably constructed from a translucent material such that the light of thestatus indicators 936 is transmitted to the surface of the actuation member. A plurality ofshort posts 940 are provided in theactuation member 912 directly above thestatus indicators 936 to operate as light pipes for the linear array of status indicators. Thedisplay PCB 938 comprises a tab 952 having aconnector 954 on the bottom side for connecting thedisplay PCB 938 to themain PCB 924.
Theactuation member 912 comprises anotch 942, which separates alower portion 944 and anupper portion 946 of the actuation member. Upon actuation of thelower portion 944 of theactuation member 912, the dimmer 900 causes the connected lighting load to toggle from on to off (and vice versa). Preferably, ablue status indicator 948 and anorange status indicator 950 are located behind thelower portion 944, such that the lower portion is illuminated with blue light when the lighting load is on and illuminated with orange light with the lighting load is off Actuation of theupper portion 946 of theactuation member 912, i.e., above thenotch 942, causes the intensity of the lighting load to change to a level responsive to the position of the actuation on theactuation member 912. Thestatus indicators 936 behind thestatus markers 112 are illuminated to display the intensity of the lighting load as with the previously-discussedtouch dimmer 100.
Fig. 20 is an enlarged partial bottom cross-sectional view of a thin touchsensitive actuator 960 according to a sixth embodiment of the present invention. The touchsensitive actuator 960 comprises anactuation member 962 having twoposts 964 for actuating the touchsensitive device 930. A plurality ofstatus indicators 966 are mounted on aflexible display PCB 968, i.e., a flexible status indicator support board, which theposts 964 of theactuation member 962 are operable to actuate the touchsensitive device 930 through. Thestatus indicators 966 are preferably blue LEDs and are arranged along the length of theactuation member 962. Preferably, theactuation member 962 is constructed from a translucent material such that the light of thestatus indicators 966 is transmitted to the surface of the actuation member.
Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred, therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.

Claims

A user interface for a lighting control, the user interface comprising:
a touch sensitive front surface;
a touch sensitive device responsive to a point actuation on the touch sensitive front surface, the point actuationcharacterized by a position and a force, the touch sensitive device comprising a resistive divider and an output for providing a control signal representative of the position of the point actuation;
a usage detection circuit operatively coupled to the output of the touch sensitive device for determining if the point actuation is presently occurring;
a stabilizing circuit operatively coupled to the output of the touch sensitive device and comprising an output, the stabilizing circuit comprising a whacking-grade capacitor for stabilizing the control signal of the touch sensitive device, the capacitor operable to charge and discharge through the resistive divider of the touch sensitive device, such that the control signal is representative of the position of the point actuation; and
a controller coupled to the usage detection circuit and the output of the stabilizing circuit, the controller operable to determine when the point actuation is presently occurring in response to the usage detection circuit, the controller responsive to the control signal only when the point actuation is presently occurring.
The user interface of claim 1, wherein the controller has first and second inputs
and the output of the touch sensitive device comprises a DC voltage coupled across the resistive divider, such that the output is operable to provide an output voltage representative of the position of the point actuation along the longitudinal axis;
the capacitor coupled between the first input of the controller and a circuit common, the first capacitor operable to charge and discharge through the resistive divider of the touch sensitive device to stabilize the first control signal, the user interface further comprising:
a first switch responsive to the controller and coupled between the output of the touch sensitive device and the first input of the controller; and
a second switch responsive to the controller and coupled between the output of the touch sensitive device and the second input of the controller;
wherein the controller is operable to render the second switch conductive, such that the voltage at the second input is representative of whether the touch sensitive front surface is presently being actuated, and to render the first switch conductive such that the capacitor is operable to stabilize the output voltage of the touch sensitive device and the voltage at the first input is representative of the position of the point actuation along the longitudinal axis.
The user interface of claim 2, further comprising:
a second capacitor coupled between the second input of the controller and the circuit common; and
a first resistor coupled between the second input of the controller and the circuit common, such that the first resistor is coupled in parallel electrical connection with the second capacitor;
wherein when the controller controls the second switch to be conductive, the parallel combination of the second capacitor and the first resistor is coupled between the longitudinal resistive element and the circuit common.
The user interface of claim 3, wherein the controller renders the first and second switches conductive on a complementary basis.
The user interface of claim 4, wherein the controller renders the first and second switches conductive on a periodic basis, such that the first switch is conductive for a substantially long period of time and the second switch is conductive for a substantially short period of time.
The user interface of claim 5, wherein the second switch is rendered conductive for approximately 1% of the time.
A load control device comprising the user interface of claim 1 for controlling an amount of power delivered to an electrical load from an AC power source, the load control device further comprising:
a semiconductor switch operable to be coupled in series electrical connection between the source and the load, the semiconductor switch having a control input for controlling the semiconductor switch between a non-conductive state and a conductive state;
wherein the controller is operatively coupled to the control input of the semiconductor switch for controlling the semiconductor switch between the non-conductive state and the conductive state.
The load control device of claim 7, wherein the control signal comprises a DC voltage representative of the position of the point actuation along a longitudinal axis of the touch sensitive front surface.
The load control device of claim 8, wherein the usage detection circuit is operable to determine if the position of the point actuation is presently changing along the longitudinal axis of the touch sensitive front surface.
The load control device of claim 9, wherein the touch sensitive device comprises a single output for providing the DC voltage representative of the position of the point actuation along the longitudinal axis of the touch sensitive front surface.
The load control device of claim 8, wherein the usage detection circuit is operable to determine if the position of the point actuation is presently changing along a lateral axis of the touch sensitive front surface.
The load control device of claim 11, wherein the output of the touch sensitive device comprises a first output for providing a first DC voltage representative of the position of the point actuation along the longitudinal axis, and a second output for providing a second DC voltage representative of the position of the point actuation along the lateral axis.